To ensure shrink-wrapping of the necessary quality, it is usual to have a shrink tunnel with consecutive heating or tunnel zones each with its own heating system. The heating systems are typically electric or gas-powered heating systems that blow hot air. These zones follow each other in the direction of transport of packaging units or containers through the shrink tunnel.
Each tunnel zone is kept at a target operating temperature required to shrink on the shrink film. This temperature is typically in a range between 195° C. and 210° C., preferably around 200° C. The heating systems maintain these temperatures even when no packages or package groups are being moved through the shrink tunnel. These interruptions in the flow of packages can arise, for example, as a result of malfunctions in the system components or machines before or after the shrink tunnel.
During such an interruption, no new packages are entering the shrink tunnel. This means that the cost of maintaining the desired temperature becomes lower than it would be if packages were in fact entering the shrink tunnel. However, although there is an energy savings associated with having no packages enter the tunnel, the net effect is still wasted gas and excess carbon dioxide emission.